Plunger switch



y 9, 1952 G. s. ELLITHORPE 2,605,375

PLUNGER SWITCH Filed May 20, 1950 2 SHEETS-SHEET 1 INVENTOR: GILBERT S. ELLITHORPE gli ujdaw ATT'YS y 1952 G. s. ELLITHORPE' 2,605,375

- PLUNGER SWITCH Filed May 20. 1950 I 2 SHEETSJ-SHEET 2 FIG.7

' INVENTOR: GILBERT S. ELLITHORPE ATT'YS Patented July 29, 1952 UNITED- "PLUNGER SWITCH Gilbert; s.= Enimor ei. Chicago. n1;, Sims to, Garter? Parts; Company;- Ghicagoh 111., a 001110 ration of lllinois larl'yto--improvements in -phinger swifich construe tion's'of t his type; v

"ms-mam objects dfithis in-veniian are imamvide a -siitrp1ified-p1ungerswitch consiiruct-ionfeind assembly to provide an improvefi-pl unger swim during" each" cperaiiiOn of the 'swit'dh; to provide an improved 'termina'i' fer pliungerswitc'hs'; 150' prqvide" an'-impr6ved-' reciprocating finta'cfidi'ior' plunger switches; -topToVidanimprovQd plunger; contactor; and 'terminal", 'as'sembiy' for plunger switches: and' to providean' improvedmlunger switch assembly'adapiqd fbr simpiiiied mountingiri'a waifor'iparielapertura ploded or separatevd're'lation, the parts being" shown irr'thesequenceoftheir assembly:

Fig. 2 is a longitudinal sectional view-arms improved plunger switch sh'dwifig its 'infierm-IE,

constructionv and the manner of, its mounting'tih ofFig. 2." v Fig. 41's as transverse sectionalvi'ew-af the" 1m provediswitch as taiken" QHHYIBZ 4 "4"'"ofFig.;2t

Fig. 511s 7a transverse" sectional view'dfffih'e same" astak'en' QnIine' 55"of'Fig, 2.1

Fig. 6; is' .2; :perspsctive viwshowmg 'ths relationship: of: the unmoved switcrr'.terminaisrand" cdritafctdr element witwthspa'rts beirigishowni'n outsici'rcu'itrclds'ing position, the cofitactor 15E;-

' inggalsb shownin' diitted outline awn intermedicontour, extending into th body from on en iltim wherein-a- Wiping: en'gagemeritof- "the' eant'ac tor" r substantial}? the opposite end'ithezfeof'" ipanrtof diametricauw spaced,"para11eI;-..a;xiany x-tendin'ig,v terminals 3 arid dy'suitdbiy mlififitdfwithmifihi rem: 01: closed :emt tlircii sna axiar stiiitatilel wardl'y, fiibm. 'the reaxzwarfdl. end thereof.- Where;

3 for the contactor arms during their reciprocal movement as will be hereafter described.

The contactor is a cup-shaped member, stamped from a suitable conductor metal, and is disposed with its cupped side facing outwardly, the arms 1 and 8 projecting radially from the margin of the cup rim in diametrically opposite directions. "AlsShoviii the outer' surfaces of, the contactor arms" are rounded and the arms are of such a length as to extend into the guide grooves 2| when the contactor is assembled in v the body or base I.

to be adequately spaced from the terminals 3 and Also the diameter of the inwardly formed cupped portion is preferably of a size to fit within the end of the-helically coiled-f I biasing spring 6, which in turn-is of a diameter the bottom of the body I. V in place at its upper end by means of the washer In a single acting switch, such as that shown,

4 when the spring is fully compressed. Thusthe contactor 5 is centrally supported by the spring and at the same time securely holds the upper end of the spring bodyl.

aligned with the axis of the The inneror lowerend of the compression spring 6 is secured in the base orbody |;by.

means of acentral spring seat and contactor stop $12.. which extends axially inward from the bottom of the body. This spring seat is in the formzof a truncated cone having a base diameter only slightly lessthan theinner diameter of, the. spring 6, so that the spring may be easily seated during assembly, and the diameter of the upper end is preferably at least the diameter of the bottom* side of, the cupped contactor 5. The

. height of'the spring seat, in the embodiment shown, is such that when the contactor is pressed intothe body to the limitof its stroke it will the, upper endof the-body I, with its arms I andBin engagement with the upper ends of the terminals, by the spring 6, is actuated by the plunger {0, and the inner end j23 of the enlarged body portion ;II of the plunger is preferb ha e t se s uar y. in the c p g n:

utheilength'of. the spring seat 22 is made sufficient to stop the inward movement of the contactor'5 -before' its arms can engage the lugs 21. However, if a double acting switch is desired, where'the circuit between the terminals is to be v closed at-each end of the plunger-contactor tral portion of the contactor. :Thus upon reciprocation of the plunger'the contactor is held norm al t'o the v,axisof its movement, and disengage merit of thecontactor arms from; the two terminals is simultaneous. Also, as shown, the cupped c ntr1 i 9t th semest r and t e shaped inner end of the plunger are annularin form to permitrotation of one part-relativeto the other ontheir common axis. 7

Irithev form shownith'e terminals 3 and dare fiat'sheet metal strips, punched. or otherwise formed from v a. suitable conductor material, adapted to be fitted-lengthwise in the body' slots [8 and I9, and areof such length as to'eXtend through the'body I from the front end thereof and-project outwardlyfrom the bottom of the body to provide attachment portions for suit able leads or conductors. Each terminal has its central body portion cut away, as at-'24, to provide arelatively wide clearance path through which the contactor arms extend and theupper end 25 of each terminal is formed :to' span the clearance path, and provide aseat. 26-for the respective,- contactor arm. The clearance path in the terminal is of greater width than the guide, groove 2|, formed in thebase or body I, and the length of the clearance'path is sufficient to allow a full inward stroke of the. contactor 5 without engagement with the terminal, thegu'ide groove cbnfiningthecontactor movement to a stroke, the length of the spring seat may be shortened to permit such a result.

In order to provide a wiping contact between theterminals and the respective contactor arms, at the upper or outer end of the contactor stroke, theseat 26 of each terminal is offset laterally from'the axial plane of the contactor movement, or from the center-line of the terminal, as shown in Fig, 3, and the innermargin 28 of the terminal-,at the upper end of the clearance path, is slanted to cross the center-line of the terminal at an angle of approximately 45. Thus, as the contactor approaches the outer end of its stroke,

the arms 7 and 8, which are guided in a plane normal to the terminals by the guide grooves 2|, engage the slanted terminal margins 28 before reaching the contact seats 26. Theterminals 3 and4, which are indentical in form, are mounted face to face in the base or body 1 so that the slanted inner margins extend in the same angular direction and the wiping contact action is afforded by a slight rotation of the contactor 5 on its axis ofreciprocation, as the arms 1 and 8 slide along the slanted margins '28 to reach the seats 26. This is illustrated in Fig. 6 where the contactor 5 is shown in dotted outline at an intermediate position, normal to the terminals, end in solid outline at the rotated seated posi- Such turning'action of the contactor 5 is permitted by widening each guide groove 2|, on the side toward which the respective arm moves to engag its terminal seat 26, in the upper portion of the path of'the contactor. As shown, the margin of the groove 2 i, between the widened upper portion and the narrow lower portion, is inclined lengthwise with respect to the axis of the body I, as fat 29,"and,this inclined "portion is located in- Wardly, from the upper end of the body I, a distahce sumcient to permit the contactor to move through about one-half the length of its stroke, in the inward direction, before the contactor arms will be engaged by the sides of the guide groove; Thus when the contactor is moved'inwardlyby theplunger It, to open the circuit be.-

tweenthe terminals, "it will retain its partially is opened, will then return the contactor to its end of the stroke.

'- The switch elements are held in assembled re lation by means of the cap or bonnet I2 which fits over the upper or front end of the base I and seats on the washer 9, the cap I2 having a radiallyfianged end. portion 30 for that purpose. The clamping lugs I3 and I4 extend axially from the margin of the flanged portion 30, on diametrically opposite sides of the cap, and embrace the'sides of'the body I where shoulders 3| are formed by reducing the transverse thickness of the body-asshown in Fig; 3. The cap is secured by turning theends of the lugs under the shoulders. The plunger 16, which extends through the end opening I5 of the cap, is held-in the assembly by means of the shoulder 32, formed by the enlarged portion I I, which is engaged by the inturned end flange 33' surrounding the opening 'As shown in Figs. 2, 3, 4 and 8, the plunger switch assemblymay be mounted in the opening of a plate or panel by means of the mounting ring or lock ring H which fits over the end of the cap or bonnet I2 and which has an annular flange 34, adapted to bear onthe outer margin of the opening, and axially extending lock lugs 35 adapted to enter the opening and engage the cap I2. For this purpose the cap I2 is provided with cam arms 36 which extend axially rearward from the-flange 30 on diametrically opposite sides of the cap between the clamping arms I3 andl4. The diameter of the cap I2 between" the cam arms 36 is greater than that between the clamp arms I3 and I4 by substantially twice the'thickness of the arms, as shown in Fig. 9, and each cam arm is provided with an axially inclined margin 31 on which the mounting ring lugs 35 engageand ride to draw the ring and cap toward each other. The locklugs 35 on the ring I? are formed by turning the ends of axially extending fingers inwardly upon themselves and the ring is made so that the diameter between the inturncd finger ends is substantially the same as the external diameter of the cap I2 across the clamp arms I3 and I4. Thus the ring may be applied with the fingers passing over the cap I2 at any location between the cam 'arms 38 and the ring and cap are locked together by merely turning the ring in a clockwise direction. A stop 38 is provided at the high end of the inclined cam surface of each cam arm to keep the lock ring lugs from being turned beyond the cam surface 31. I

.The mounting ring is also provided with a plurality of angularly spaced axially extending spring fingers 39 which are designed to enter the opening in which the switch assembly is mounted and to bear resiliently outward on the edge of the opening to hold the assembly in thereby increase the spring tension-of the fingers in their function of frictionally gripping the edges of the opening in which the switch is mounted.

The improved mounting ring arrangement is particularly adapted for easy and rapid mounting of the plunger switch after the wiring con nections to the switch have been made. The mounting is effected by passing the switch, plunger first; through the opening in which itis to be mounted, from the rear side thereof; then the'cap or bonnet and turning the ring to lock it onto the cap; and finally pushing the assembly back into the opening and snapping the mounting ring into place with its flange abutting the-outer margin of the opening. Thus the need for screws threaded bushings and lock nuts or rings, and mounting plates is completelyobviated thereby saving considerably in mounting time and cost. v

The main advantages of thi invention reside in the-provision for a wiping contact or engagement between the contactor and the switch terminals whereby pitting and burning at the point of final contact .is materially reduced, thereby resulting in more efficient switch action and longer switch life; and in the improved rotating contactor arrangement whereby an efiicient wiping action, under direct pressure from the actuatin'g or biasing spring, is obtained.

Other principal advantages are to be found in the improved switch assembly means, and its combination with the simpl clamping ring or friction fastener, whereby a' plunger switch can be more easily and quickly mounted in a suitable opening of a wall panel, without the need for tools or screw fasteners, and after attachment of the connecting wires hasbeen made.

Although but one specific embodiment of this invention is herein shown and described it will be understood that details of the construction shown may be altered or omitted without departing from the spirit of th invention as defined by the following claims:

Iclaim:

1. A plunger switch comprising a dielectric body having a passage opening to one end of the body, a plunger extending into said passage and reciprocable therealong, a contactor disposed in said passage and axially shiftable with said plunger, said contactor having a pair of radial arms, a pair of spaced rigid terminals each having a contact portion extending across the path of a respective arm along an acute angle relative to said path in the axial direction of said passage, meansnormally biasing said plunger and contactor toward the open end ofisaid passage,

and a pivotal connection between said contactor and saidv plunger adapted to permit angular movement of the contactor in a plane normal to the axis of the plunger whereby said contactor arms will slide along the contacting portions of said terminals when engaged therewith.

2. A plunger switch comprising a'dielectric body having a passage opening to one end of the body, a plunger extending into said passage and reciprccable therealong, a contactor disposed in said passage and axially shiftable with said plunger, said contactor having a pair of radial arms, a pair of spaced terminals each having a rigid contact portion extending across the path of a respective arm along an acute angle relative to said path in the axial direction of saidpassage, eachv contact portion terminating in an angularly offset seat for. the respective contact arm, means. normally biasing said plunger and. contactor toward the Open nd of said passage, and a pivotal plunger adapted to permit angular shifting movement of the contactorin a plane normal to the axis of the plunger whereby said contactor arms will slide along the contacting portions of said terminals and engage in the respective angularly offset seats.

"3AA plunger switch comprising a dielectric body having a passage opening to one end of the body, a plunger disposedin said passage and adapted to be moved axially therealong, a contactor movable axially in said passage and having a pair of arms extending radially relative to the axis of said passage, said contactor having connection with said plunger for reciprocal actuation thereby, a pair of spaced terminals, a rigid contact portion on each terminal extending transversely across the path of a respective one of said contactor arms and along an acute angle relative to said path in the axial direction thereof, and resilient means normally biasing said plunger and contactor toward the open end of said passage, said, contactor being shiftable angularly on'its axis of reciprocation upon engagement with said terminal contact portions.

4. A plunger switch comprising a dielectric body having a passage opening to one end of the body, a plunger disposed in said passage and adapted to be moved axially therealong, a contactor movable axially in said passage and having a pair of arms extending radially relative to the axis'of said passage, said contactor having connection with said plunger for reciprocal actuation thereby, a pair of spaced terminals,

a rigid contact portion on each terminal extending transversely across the path of a respective one of said contactor arms and along an acute angle relative to said path in the axial direction thereof, and resilient means normally biasing said plunger and contactor toward the open end of said passage, said contactor being shiftable angularly on its axis of reciprocation upon engagement with said terminal contact portions, and the contact portion of each terminal terminating in an angularly oifset seat for the respective contact arm.

5. A plunger switch comprising a dielectric body having a passage opening to one end of the body, a cylindrical plunger extending into said passage and movable axially therealong, a contactor disposed at the inner end of said plunger and having a pair of diametrically opposite radial arms, said contactor being axially shiftable in said body with said plunger and rotatable on theplunger axis, a pair of terminals disposed in said passage and each having a rigid slanted contact portion extending across the path of a respective contactor arm, said contact portions being inclined in the same angular direction relative to the respective paths of said arms, and means normally biasing said plunger and contactor toward the open end of said passage.

6. A plunger switch comprising a dielectric body having a passage opening to one end of the body, a cylindrical plunger extending into said passage andmovable axially therealong, a contactor disposed at the inner end of said plunger and having a pair of diametrically opposite radial arms, said contactor being axially shiftable in said body with said plunger and rotatable on the plunger axis, a pair of fiat elongate terminals each disposed lengthwise in said passage opposite a respective arm and lying in a plane normal to the plane of movement of the arm, each terminal being cut away in its central portion to receive the respective arm and to provide an axially extending clearance path therefor, the margin of the'cutaway portion of each terminal adjacent one end thereof being inclined axially across the path of the contactor arm and terminating in an angularly ofiset contact seat, said inclined margins extending in the same angular direction, and means normally biasing said contactor 8 i and plunger toward the open end of said body passage.

7. A plunger switch comprising a dielectric body having a central passage opening to the forward end of the body and adapted to receive a reciprocable plunger, a pair of rigid fiat metal terminals mounted in said body in parallel relation one on each of diametrically opposite sides of said passage, each terminal being cut away in its central portion to provide an axial clearance path for a contactor arm extending therethrough and reciprocable in a plane normal thereto, a plunger extending into said body passage and movable axially between said terminals, a forwardly facing annular cup-like contactor disposed at the inner end of said plunger and having opposed radial arms extending from its rim and through the clearance paths of said terminals respectively, said plunger having an annular inner end portion adapted to fit into the cupped portion of said contactor and said contactor being rotatable on the axis of said plunger, an axially inclined contact portion adjacent one end of the-clearance path of each terminal, said inclined contact portions being diametrically opposite each other and extending across the paths of the respective contact arms in the same angular direction and each terminating in an angularly offset contact seat, and means in said body normally biasing said contactor and plunger to- Wardthe forward end of said body.

8. A plunger switch comprising a dielectric body having a central passage opening to the forward end of the body and adapted to receive a reciprocable plunger, a pair of flat metal terminals mounted in said body in parallel relation one on each of diametrically opposite sides of said passage, each terminal'being cut away in its central portion to provide an axial clearance path for a contactor arm extending therethrough and reciprocable in a plane normal thereto, a plunger extending into said body passage and movable axially between said terminals, a forwardly facing annular cup-like contactor disposed at the inner end of said plunger and having opposed radial arms extending from its rim and through the clearance paths of said terminals respectively, said plunger having an annular inner end portion adapted to fit into the cupped portion of said contactor and said contactor being rotatable on the axis of said plunger, an axially inclined contact portion adjacent the forward end of the clearance path'of each terminal, said inclined contact portions extending across the paths of the respective contact arms in the same angular direction and each terminating in an angularly ofiset contact seat, and means in said body normally biasing said contactor and plunger toward the forward end, of said body Where said contactor arms are engaged in said contact seats.

9. A plunger switch comprising a body of insulating material having a plunger passage therein opening to the forward end of the body, a plunger extending into said passage and having an enlarged inner end portion, said plunger being reciprocable along the axis of said passage,

a contactor at the inner end of said plunger and reciprocable therewith, said contactor having a pair of angularly spaced radial arms, a pair of terminals mounted in said body from the forward end thereof and disposed alongside the path of the plunger, each of said terminals hav ing a contact portion extending angularly across the path of a respective contactor arm adia- 'cent a common end of its movement-patm; said contact portions being inclinedyaxially inthe same angular direction, a spring in said plunger passage normally biasing said contactor and plunger toward the forward end-of the passage, .acap memberdisposed overthe forward end-of said body and secured thereto, said capmember having anopeningthrough which the'outer end of said plunger proje cts'said 'c'ap' opening being of less diameter than the inner end portion of the plunger'and said cap. beinggadapted to confine theaplunger, terminals; and gco'ntactor; Within said body; and a radially vflangedmountingring disposed telescopingly over said cap member and having releasable interlocking connection therewith, said mounting ring having a plurality of angularly spaced rearwardly extending spring fingers on its inner margin adapted to frictionally engage the peripheral edge of a panel opening in which the plunger switch is inserted.

10. A plunger switch assembly comprising a switch housing enclosing a plunger actuated switch mechanism and having a reciprocable plunger projecting axially therefrom, a cap secured on the end of said housing and having an opening through which the projecting end of the plunger extends, said cap being adapted to retain the plunger and switch mechanism within the housing, a mounting ring adapted to fit telescopingly over said cap and having an inwardly projecting radial flange for engaging said cap endwise, means on said ring adapted to releasably interlock with cooperative means on said cap for securing said ring and cap together, and a plurality of angularly spaced resilient fingers extending rearwardly from the said mounting ring, said fingers being adapted to frictionally engage the peripheral edge of an opening into which the switch housing and mounting ring are inserted rear end first.

11. A plunger switch assembly comprising a switch housing enclosing a plunger actuated switch mechanism and having a reciprocable plunger projecting axially therefrom, a cap secured on the end of said housing and having an opening through which the projecting end of the plunger extends, said cap being adapted to retain the plunger and switch mechanism within the housing, a mounting ring adapted to fit telescopingly over said cap and having an inwardly projecting radial flange for engaging said cap endwise, means on said ring adapted to releasably interlock with cooperative means on said cap for securing said ring and cap together, and a plurality of angularly spaced resilient fingers extending rearwardly from said mounting ring, said fingers having inwardly turned ends embracingly engaging said cap and housing, and said fingers being radially yieldable intermediate their ends for frictionally engaging the peripheral edge of an opening into which the switch housing and mounting ring are inserted rear end first.

12. In a plunger switch comprising a hollow body, a plunger reciprocable along a predetermined axis in said body and projecting outwardly therefrom, and spring means normally biasing said plunger in the outward direction, the combination of a contactor axially reciprocable with said plunger and having a pair of angularly spaced radial arms, said contactor being rotatable on the axis of reciprocation, said body having axial guide channels in its inner side wall for receiving said arms and adapted to confine said arms to a predetermined path during a pornels. 3

- 13. ;In; a odv u e r r c pro a al ae a prsdeterr im-@31 in said hedyi n reies= i s QF TQT ly 'thereirom and springmeans normally biasing said plunger in the outward direction, the'com- 1 bination of a contactor axially reciprocable with said plunger and having a pair of angularly spaced radial arms, said contactor being rotatable on the axis of reciprocation, said body having axially extending guide channels in its inner wall for receiving said arms and adapted to confine said arms to a predetermined path during a portion only of their reciprocal movement, and a pair of terminals mounted within said body and each having a contact portion disposed across the path of a respective arm, said contact portions being inclined axially in the same angular direction and terminating in an angularly offset contact seat, and said contact portions being located adjacent one end of the path of reciprocation of the contactor beyond the area of influence of said guide channels, and said body having angularly inclined means extending from the end of each guide channel toward the respective contact seat for leading the contactor arms angularly into said channels when the said arms are disengaged from said contact seats.

14. In a plunger switch comprising a body having a plunger passage therein, a plunger reciprocable along the axis of said passage and projecting outwardly therefrom, and means normally biasing said plunger in the outward direction, the combination of a pair of flat parallel axially extending terminals mounted in said body one on each side of said passage and each having a cut-out portion intermediate the ends of the passage to provide an axially extending clearance path for a contact arm projecting therethrough and movable in a plane normal thereto, the margins of the cut-out portions of said terminals adjacent a common end thereof being axially inclined in the same angular direction across the said clearance path, a contactor axially reciprocable in said passage with said plunger and rotatable on the axis thereof, said contactor having a pair of oppositely disposed radial arms respectively extending through the clearance paths of said terminals, and said body having guide means registered with the cut-out portion of each terminal and adapted to confine the movement of said contactor arms to a plane normal to the planes of said terminals in that portion of their path beyond the zone of the inclined margins of the terminal clearance paths.

15. A plunger switch comprising a body of dielectric material having a plunger passage therein opening to the forward end of the body, a plunger extending into said passage, said plunger being reciprocable along the axis of said passage, a contactor at the inner end of said plunger and reciprocable therewith, said contactor having a pair of angularly spaced radial arms, a pair of terminals mounted in said body and disposed alongside the path of said plunger, each of said terminals having rigid slanted contact portions extending angularly across the path of 1 1 a respective contactor arm adjacent a common end of its movement'pa'th, said contact portions being inclinedaxially in the same angular direction and said contactor being shiftable angularlyon the axis of said'plunger upon engagement with said inclined contact portions, means for limiting the angular'movefnent of said contactor, means for reversing the angular movement of said contactor and returning said arnis to their axial paths of reciprocatory motion aftcr disengagement of said contactor 'from the slanted contact portion of said terminals, and means in said plunger passage normally biasing said contactor" and plunger toward the forward end of the plunger passage.

GILBERT S. ELLITHORPE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 2,065,904 Meuer Dec. 29, 1936 2,083,118 Goldstone June 8, 1937 2,519,329 Woodward Aug. 15, 1950 

